Tunnel magnetoresistive sensor having conductive ceramic layers

ABSTRACT

In one general embodiment, an apparatus includes a sensor having an active tunnel magnetoresistive region, magnetic shields flanking the tunnel magnetoresistive region, and spacers between the active tunnel magnetoresistive region and the magnetic shields. The active tunnel magnetoresistive region includes a free layer, a tunnel barrier layer and a reference layer. At least one of the spacers includes an electrically conductive ceramic layer. The presence of the electrically conductive ceramic layer enables current-perpendicular-to-plane operation, while enhancing wear resistance and resistance to deformities of the thin films.

BACKGROUND

The present invention relates to data storage systems, and moreparticularly, this invention relates to tunnel magnetoresistive (TMR)sensors having conductive ceramic layers.

In magnetic storage systems, magnetic transducers read data from andwrite data onto magnetic recording media. Data is written on themagnetic recording media by moving a magnetic recording transducer to aposition over the media where the data is to be stored. The magneticrecording transducer then generates a magnetic field, which encodes thedata into the magnetic media. Data is read from the media by similarlypositioning the magnetic read transducer and then sensing the magneticfield of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has led to increasing the track and linear bitdensity on recording tape, and decreasing the thickness of the magnetictape medium. However, the development of small footprint, higherperformance tape drive systems has created various problems in thedesign of a tape head assembly for use in such systems.

In a tape drive system, the drive moves the magnetic tape over thesurface of the tape head at high speed. Usually the tape head isdesigned to minimize the spacing between the head and the tape. Thespacing between the magnetic head and the magnetic tape is crucial andso goals in these systems are to have the recording gaps of thetransducers, which are the source of the magnetic recording flux in nearcontact with the tape to effect writing sharp transitions, and to havethe read elements in near contact with the tape to provide effectivecoupling of the magnetic field from the tape to the read elements.

Minimization of the spacing between the head and the tape, however,induces frequent contact between the tape and the media facing side ofthe head, causing tape operations to be deemed a type of contactrecording. This contact, in view of the high tape speeds and tapeabrasivity, quickly affects the integrity of the materials used to formthe media facing surface of the head, e.g., causing wear thereto,smearing which is known to cause shorts, bending ductility, etc.Furthermore, shorting may occur when an asperity of the tape media dragsany of the conductive metallic films near the sensor across the tunneljunction.

SUMMARY

An apparatus according to one embodiment includes a sensor having anactive tunnel magnetoresistive region, magnetic shields flanking thetunnel magnetoresistive region, and spacers between the active tunnelmagnetoresistive region and the magnetic shields. The active tunnelmagnetoresistive region includes a free layer, a tunnel barrier layerand a reference layer. At least one of the spacers includes anelectrically conductive ceramic layer. The presence of the electricallyconductive ceramic layer enables current-perpendicular-to-planeoperation, while enhancing wear resistance and resistance to deformitiesof the thin films.

A thickness of the ceramic layer is preferably at least 2 nanometers,and more preferably at least 10 nanometers. These thicknesses helpensure adequate crystallinity.

As an option, both spacers may include an electrically conductiveceramic layer. This further enhances durability and robustness of thesensor.

A durable layer may optionally be present above an upper one of theshields and/or below a lower one of the shields, the durable layer beingharder than the shield nearest thereto. This further enhances durabilityand robustness of the sensor.

An apparatus according to another embodiment includes a sensor having anactive tunnel magnetoresistive region, magnetic shields flanking thetunnel magnetoresistive region, spacers between the tunnelmagnetoresistive region and the magnetic shields, and an electricallyconductive ceramic layer between the active tunnel magnetoresistiveregion and at least one of the spacers. The active tunnelmagnetoresistive region includes a free layer, a tunnel barrier layerand a reference layer. The presence of the electrically conductiveceramic layer enables current-perpendicular-to-plane operation, whileenhancing wear resistance and resistance to deformities of the thinfilms.

Any of these embodiments may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head, adrive mechanism for passing a magnetic medium (e.g., recording tape)over the magnetic head, and a controller electrically coupled to themagnetic head.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram of a simplified tape drive systemaccording to one embodiment.

FIG. 1B is a schematic diagram of a tape cartridge according to oneembodiment.

FIG. 2 illustrates a side view of a flat-lapped, bi-directional,two-module magnetic tape head according to one embodiment.

FIG. 2A is a tape bearing surface view taken from Line 2A of FIG. 2.

FIG. 2B is a detailed view taken from Circle 2B of FIG. 2A.

FIG. 2C is a detailed view of a partial tape bearing surface of a pairof modules.

FIG. 3 is a partial tape bearing surface view of a magnetic head havinga write-read-write configuration.

FIG. 4 is a partial tape bearing surface view of a magnetic head havinga read-write-read configuration.

FIG. 5 is a side view of a magnetic tape head with three modulesaccording to one embodiment where the modules all generally lie alongabout parallel planes.

FIG. 6 is a side view of a magnetic tape head with three modules in atangent (angled) configuration.

FIG. 7 is a side view of a magnetic tape head with three modules in anoverwrap configuration.

FIG. 8A is a partial media facing side view of a sensor stack, accordingto one embodiment.

FIG. 8B is a partial cross-sectional view taken from Line 8A-8B of FIG.8A.

FIG. 9 is a partial side view of a sensor stack, according to oneembodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred embodiments ofmagnetic storage systems, as well as operation and/or component partsthereof.

In one general embodiment, an apparatus includes a sensor having anactive tunnel magnetoresistive region, magnetic shields flanking thetunnel magnetoresistive region, and spacers between the active tunnelmagnetoresistive region and the magnetic shields. The active tunnelmagnetoresistive region includes a free layer, a tunnel barrier layerand a reference layer. At least one of the spacers includes anelectrically conductive ceramic layer. The presence of the electricallyconductive ceramic layer enables current-perpendicular-to-planeoperation, while enhancing wear resistance and resistance to deformitiesof the thin films.

In another general embodiment, an apparatus includes a sensor having anactive tunnel magnetoresistive region, magnetic shields flanking thetunnel magnetoresistive region, spacers between the tunnelmagnetoresistive region and the magnetic shields, and an electricallyconductive ceramic layer between the active tunnel magnetoresistiveregion and at least one of the spacers. The active tunnelmagnetoresistive region includes a free layer, a tunnel barrier layerand a reference layer. The presence of the electrically conductiveceramic layer enables current-perpendicular-to-plane operation, whileenhancing wear resistance and resistance to deformities of the thinfilms.

FIG. 1A illustrates a simplified tape drive 100 of a tape-based datastorage system, which may be employed in the context of the presentinvention. While one specific implementation of a tape drive is shown inFIG. 1A, it should be noted that the embodiments described herein may beimplemented in the context of any type of tape drive system.

As shown, a tape supply cartridge 120 and a take-up reel 121 areprovided to support a tape 122. One or more of the reels may form partof a removable cartridge and are not necessarily part of the system 100.The tape drive, such as that illustrated in FIG. 1A, may further includedrive motor(s) to drive the tape supply cartridge 120 and the take-upreel 121 to move the tape 122 over a tape head 126 of any type. Suchhead may include an array of readers, writers, or both.

Guides 125 guide the tape 122 across the tape head 126. Such tape head126 is in turn coupled to a controller 128 via a cable 130. Thecontroller 128, may be or include a processor and/or any logic forcontrolling any subsystem of the drive 100. For example, the controller128 typically controls head functions such as servo following, datawriting, data reading, etc. The controller 128 may include at least oneservo channel and at least one data channel, each of which include dataflow processing logic configured to process and/or store information tobe written to and/or read from the tape 122. The controller 128 mayoperate under logic known in the art, as well as any logic disclosedherein, and thus may be considered as a processor for any of thedescriptions of tape drives included herein, in various embodiments. Thecontroller 128 may be coupled to a memory 136 of any known type, whichmay store instructions executable by the controller 128. Moreover, thecontroller 128 may be configured and/or programmable to perform orcontrol some or all of the methodology presented herein. Thus, thecontroller 128 may be considered to be configured to perform variousoperations by way of logic programmed into one or more chips, modules,and/or blocks; software, firmware, and/or other instructions beingavailable to one or more processors; etc., and combinations thereof.

The cable 130 may include read/write circuits to transmit data to thehead 126 to be recorded on the tape 122 and to receive data read by thehead 126 from the tape 122. An actuator 132 controls position of thehead 126 relative to the tape 122.

An interface 134 may also be provided for communication between the tapedrive 100 and a host (internal or external) to send and receive the dataand for controlling the operation of the tape drive 100 andcommunicating the status of the tape drive 100 to the host, all as willbe understood by those of skill in the art.

FIG. 1B illustrates an exemplary tape cartridge 150 according to oneembodiment. Such tape cartridge 150 may be used with a system such asthat shown in FIG. 1A. As shown, the tape cartridge 150 includes ahousing 152, a tape 122 in the housing 152, and a nonvolatile memory 156coupled to the housing 152. In some approaches, the nonvolatile memory156 may be embedded inside the housing 152, as shown in FIG. 1B. In moreapproaches, the nonvolatile memory 156 may be attached to the inside oroutside of the housing 152 without modification of the housing 152. Forexample, the nonvolatile memory may be embedded in a self-adhesive label154. In one preferred embodiment, the nonvolatile memory 156 may be aFlash memory device, ROM device, etc., embedded into or coupled to theinside or outside of the tape cartridge 150. The nonvolatile memory isaccessible by the tape drive and the tape operating software (the driversoftware), and/or other device.

By way of example, FIG. 2 illustrates a side view of a flat-lapped,bi-directional, two-module magnetic tape head 200 which may beimplemented in the context of the present invention. As shown, the headincludes a pair of bases 202, each equipped with a module 204, and fixedat a small angle α with respect to each other. The bases may be“U-beams” that are adhesively coupled together. Each module 204 includesa substrate 204A and a closure 204B with a thin film portion, commonlyreferred to as a “gap” in which the readers and/or writers 206 areformed. In use, a tape 208 is moved over the modules 204 along a media(tape) bearing surface 209 in the manner shown for reading and writingdata on the tape 208 using the readers and writers. The wrap angle θ ofthe tape 208 at edges going onto and exiting the flat media supportsurfaces 209 are usually between about 0.1 degree and about 3 degrees.

The substrates 204A are typically constructed of a wear resistantmaterial, such as a ceramic. The closures 204B may be made of the sameor similar ceramic as the substrates 204A.

The readers and writers may be arranged in a piggyback or mergedconfiguration. An illustrative piggybacked configuration comprises a(magnetically inductive) writer transducer on top of (or below) a(magnetically shielded) reader transducer (e.g., a magnetoresistivereader, etc.), wherein the poles of the writer and the shields of thereader are generally separated. An illustrative merged configurationcomprises one reader shield in the same physical layer as one writerpole (hence, “merged”). The readers and writers may also be arranged inan interleaved configuration. Alternatively, each array of channels maybe readers or writers only. Any of these arrays may contain one or moreservo track readers for reading servo data on the medium.

FIG. 2A illustrates the tape bearing surface 209 of one of the modules204 taken from Line 2A of FIG. 2. A representative tape 208 is shown indashed lines. The module 204 is preferably long enough to be able tosupport the tape as the head steps between data bands.

In this example, the tape 208 includes 4 to 32 data bands, e.g., with 16data bands and 17 servo tracks 210, as shown in FIG. 2A on a one-halfinch wide tape 208. The data bands are defined between servo tracks 210.Each data band may include a number of data tracks, for example 1024data tracks (not shown). During read/write operations, the readersand/or writers 206 are positioned to specific track positions within oneof the data bands. Outer readers, sometimes called servo readers, readthe servo tracks 210. The servo signals are in turn used to keep thereaders and/or writers 206 aligned with a particular set of tracksduring the read/write operations.

FIG. 2B depicts a plurality of readers and/or writers 206 formed in agap 218 on the module 204 in Circle 2B of FIG. 2A. As shown, the arrayof readers and writers 206 includes, for example, 16 writers 214, 16readers 216 and two servo readers 212, though the number of elements mayvary. Illustrative embodiments include 8, 16, 32, 40, and 64 activereaders and/or writers 206 per array, and alternatively interleaveddesigns having odd numbers of reader or writers such as 17, 25, 33, etc.An illustrative embodiment includes 32 readers per array and/or 32writers per array, where the actual number of transducer elements couldbe greater, e.g., 33, 34, etc. This allows the tape to travel moreslowly, thereby reducing speed-induced tracking and mechanicaldifficulties and/or execute fewer “wraps” to fill or read the tape.While the readers and writers may be arranged in a piggybackconfiguration as shown in FIG. 2B, the readers 216 and writers 214 mayalso be arranged in an interleaved configuration. Alternatively, eacharray of readers and/or writers 206 may be readers or writers only, andthe arrays may contain one or more servo readers 212. As noted byconsidering FIGS. 2 and 2A-B together, each module 204 may include acomplementary set of readers and/or writers 206 for such things asbi-directional reading and writing, read-while-write capability,backward compatibility, etc.

FIG. 2C shows a partial tape bearing surface view of complementarymodules of a magnetic tape head 200 according to one embodiment. In thisembodiment, each module has a plurality of read/write (R/W) pairs in apiggyback configuration formed on a common substrate 204A and anoptional electrically insulative layer 236. The writers, exemplified bythe write transducer 214 and the readers, exemplified by the readtransducer 216, are aligned parallel to an intended direction of travelof a tape medium thereacross to form an R/W pair, exemplified by the R/Wpair 222. Note that the intended direction of tape travel is sometimesreferred to herein as the direction of tape travel, and such terms maybe used interchangeably. Such direction of tape travel may be inferredfrom the design of the system, e.g., by examining the guides; observingthe actual direction of tape travel relative to the reference point;etc. Moreover, in a system operable for bi-direction reading and/orwriting, the direction of tape travel in both directions is typicallyparallel and thus both directions may be considered equivalent to eachother.

Several R/W pairs 222 may be present, such as 8, 16, 32 pairs, etc. TheR/W pairs 222 as shown are linearly aligned in a direction generallyperpendicular to a direction of tape travel thereacross. However, thepairs may also be aligned diagonally, etc. Servo readers 212 arepositioned on the outside of the array of R/W pairs, the function ofwhich is well known.

Generally, the magnetic tape medium moves in either a forward or reversedirection as indicated by arrow 220. The magnetic tape medium and headassembly 200 operate in a transducing relationship in the mannerwell-known in the art. The piggybacked MR head assembly 200 includes twothin-film modules 224 and 226 of generally identical construction.

Modules 224 and 226 are joined together with a space present betweenclosures 204B thereof (partially shown) to form a single physical unitto provide read-while-write capability by activating the writer of theleading module and reader of the trailing module aligned with the writerof the leading module parallel to the direction of tape travel relativethereto. When a module 224, 226 of a piggyback head 200 is constructed,layers are formed in the gap 218 created above an electricallyconductive substrate 204A (partially shown), e.g., of AlTiC, ingenerally the following order for the R/W pairs 222: an insulating layer236, a first shield 232 typically of an iron alloy such as NiFe (—),cobalt zirconium tantalum (CZT) or Al—Fe—Si (Sendust), a sensor 234 forsensing a data track on a magnetic medium, a second shield 238 typicallyof a nickel-iron alloy (e.g., ˜80/20 at % NiFe, also known aspermalloy), first and second writer pole tips 228, 230, and a coil (notshown). The sensor may be of any known type, including those based onMR, GMR, AMR, tunneling magnetoresistance (TMR), etc.

The first and second writer poles 228, 230 may be fabricated from highmagnetic moment materials such as ˜45/55 NiFe. Note that these materialsare provided by way of example only, and other materials may be used.Additional layers such as insulation between the shields and/or poletips and an insulation layer surrounding the sensor may be present.Illustrative materials for the insulation include alumina and otheroxides, insulative polymers, etc.

The configuration of the tape head 126 according to one embodimentincludes multiple modules, preferably three or more. In awrite-read-write (W-R-W) head, outer modules for writing flank one ormore inner modules for reading. Referring to FIG. 3, depicting a W-R-Wconfiguration, the outer modules 252, 256 each include one or morearrays of writers 260. The inner module 254 of FIG. 3 includes one ormore arrays of readers 258 in a similar configuration. Variations of amulti-module head include a R-W-R head (FIG. 4), a R-R-W head, a W-W-Rhead, etc. In yet other variations, one or more of the modules may haveread/write pairs of transducers. Moreover, more than three modules maybe present. In further approaches, two outer modules may flank two ormore inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. Forsimplicity, a W-R-W head is used primarily herein to exemplifyembodiments of the present invention. One skilled in the art apprisedwith the teachings herein will appreciate how permutations of thepresent invention would apply to configurations other than a W-R-Wconfiguration.

FIG. 5 illustrates a magnetic head 126 according to one embodiment ofthe present invention that includes first, second and third modules 302,304, 306 each having a tape bearing surface 308, 310, 312 respectively,which may be flat, contoured, etc. Note that while the term “tapebearing surface” appears to imply that the surface facing the tape 315is in physical contact with the tape bearing surface, this is notnecessarily the case. Rather, only a portion of the tape may be incontact with the tape bearing surface, constantly or intermittently,with other portions of the tape riding (or “flying”) above the tapebearing surface on a layer of air, sometimes referred to as an “airbearing”. The first module 302 will be referred to as the “leading”module as it is the first module encountered by the tape in a threemodule design for tape moving in the indicated direction. The thirdmodule 306 will be referred to as the “trailing” module. The trailingmodule follows the middle module and is the last module seen by the tapein a three module design. The leading and trailing modules 302, 306 arereferred to collectively as outer modules. Also note that the outermodules 302, 306 will alternate as leading modules, depending on thedirection of travel of the tape 315.

In one embodiment, the tape bearing surfaces 308, 310, 312 of the first,second and third modules 302, 304, 306 lie on about parallel planes(which is meant to include parallel and nearly parallel planes, e.g.,between parallel and tangential as in FIG. 6), and the tape bearingsurface 310 of the second module 304 is above the tape bearing surfaces308, 312 of the first and third modules 302, 306. As described below,this has the effect of creating the desired wrap angle α₂ of the taperelative to the tape bearing surface 310 of the second module 304.

Where the tape bearing surfaces 308, 310, 312 lie along parallel ornearly parallel yet offset planes, intuitively, the tape should peel offof the tape bearing surface 308 of the leading module 302. However, thevacuum created by the skiving edge 318 of the leading module 302 hasbeen found by experimentation to be sufficient to keep the tape adheredto the tape bearing surface 308 of the leading module 302. The trailingedge 320 of the leading module 302 (the end from which the tape leavesthe leading module 302) is the approximate reference point which definesthe wrap angle α₂ over the tape bearing surface 310 of the second module304. The tape stays in close proximity to the tape bearing surface untilclose to the trailing edge 320 of the leading module 302. Accordingly,read and/or write elements 322 may be located near the trailing edges ofthe outer modules 302, 306. These embodiments are particularly adaptedfor write-read-write applications.

A benefit of this and other embodiments described herein is that,because the outer modules 302, 306 are fixed at a determined offset fromthe second module 304, the inner wrap angle α₂ is fixed when the modules302, 304, 306 are coupled together or are otherwise fixed into a head.The inner wrap angle α₂ is approximately tan⁻¹(δ/W) where δ is theheight difference between the planes of the tape bearing surfaces 308,310 and W is the width between the opposing ends of the tape bearingsurfaces 308, 310. An illustrative inner wrap angle α₂ is in a range ofabout 0.3° to about 1.1°, though can be any angle required by thedesign.

Beneficially, the inner wrap angle α₂ on the side of the module 304receiving the tape (leading edge) will be larger than the inner wrapangle α₃ on the trailing edge, as the tape 315 rides above the trailingmodule 306. This difference is generally beneficial as a smaller α₃tends to oppose what has heretofore been a steeper exiting effectivewrap angle.

Note that the tape bearing surfaces 308, 312 of the outer modules 302,306 are positioned to achieve a negative wrap angle at the trailing edge320 of the leading module 302. This is generally beneficial in helpingto reduce friction due to contact with the trailing edge 320, providedthat proper consideration is given to the location of the crowbar regionthat forms in the tape where it peels off the head. This negative wrapangle also reduces flutter and scrubbing damage to the elements on theleading module 302. Further, at the trailing module 306, the tape 315flies over the tape bearing surface 312 so there is virtually no wear onthe elements when tape is moving in this direction. Particularly, thetape 315 entrains air and so will not significantly ride on the tapebearing surface 312 of the third module 306 (some contact may occur).This is permissible, because the leading module 302 is writing while thetrailing module 306 is idle.

Writing and reading functions are performed by different modules at anygiven time. In one embodiment, the second module 304 includes aplurality of data and optional servo readers 331 and no writers. Thefirst and third modules 302, 306 include a plurality of writers 322 andno data readers, with the exception that the outer modules 302, 306 mayinclude optional servo readers. The servo readers may be used toposition the head during reading and/or writing operations. The servoreader(s) on each module are typically located towards the end of thearray of readers or writers.

By having only readers or side by side writers and servo readers in thegap between the substrate and closure, the gap length can besubstantially reduced. Typical heads have piggybacked readers andwriters, where the writer is formed above each reader. A typical gap is20-35 microns. However, irregularities on the tape may tend to droopinto the gap and create gap erosion. Thus, the smaller the gap is thebetter. The smaller gap enabled herein exhibits fewer wear relatedproblems.

In some embodiments, the second module 304 has a closure, while thefirst and third modules 302, 306 do not have a closure. Where there isno closure, preferably a hard coating is added to the module. Onepreferred coating is diamond-like carbon (DLC).

In the embodiment shown in FIG. 5, the first, second, and third modules302, 304, 306 each have a closure 332, 334, 336, which extends the tapebearing surface of the associated module, thereby effectivelypositioning the read/write elements away from the edge of the tapebearing surface. The closure 332 on the second module 304 can be aceramic closure of a type typically found on tape heads. The closures334, 336 of the first and third modules 302, 306, however, may beshorter than the closure 332 of the second module 304 as measuredparallel to a direction of tape travel over the respective module. Thisenables positioning the modules closer together. One way to produceshorter closures 334, 336 is to lap the standard ceramic closures of thesecond module 304 an additional amount. Another way is to plate ordeposit thin film closures above the elements during thin filmprocessing. For example, a thin film closure of a hard material such asSendust or nickel-iron alloy (e.g., 45/55) can be formed on the module.

With reduced-thickness ceramic or thin film closures 334, 336 or noclosures on the outer modules 302, 306, the write-to-read gap spacingcan be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% lessthan commonly-used LTO tape head spacing. The open space between themodules 302, 304, 306 can still be set to approximately 0.5 to 0.6 mm,which in some embodiments is ideal for stabilizing tape motion over thesecond module 304.

Depending on tape tension and stiffness, it may be desirable to anglethe tape bearing surfaces of the outer modules relative to the tapebearing surface of the second module. FIG. 6 illustrates an embodimentwhere the modules 302, 304, 306 are in a tangent or nearly tangent(angled) configuration. Particularly, the tape bearing surfaces of theouter modules 302, 306 are about parallel to the tape at the desiredwrap angle α₂ of the second module 304. In other words, the planes ofthe tape bearing surfaces 308, 312 of the outer modules 302, 306 areoriented at about the desired wrap angle α₂ of the tape 315 relative tothe second module 304. The tape will also pop off of the trailing module306 in this embodiment, thereby reducing wear on the elements in thetrailing module 306. These embodiments are particularly useful forwrite-read-write applications. Additional aspects of these embodimentsare similar to those given above.

Typically, the tape wrap angles may be set about midway between theembodiments shown in FIGS. 5 and 6.

FIG. 7 illustrates an embodiment where the modules 302, 304, 306 are inan overwrap configuration. Particularly, the tape bearing surfaces 308,312 of the outer modules 302, 306 are angled slightly more than the tape315 when set at the desired wrap angle α₂ relative to the second module304. In this embodiment, the tape does not pop off of the trailingmodule, allowing it to be used for writing or reading. Accordingly, theleading and middle modules can both perform reading and/or writingfunctions while the trailing module can read any just-written data.Thus, these embodiments are preferred for write-read-write,read-write-read, and write-write-read applications. In the latterembodiments, closures should be wider than the tape canopies forensuring read capability. The wider closures may require a widergap-to-gap separation. Therefore a preferred embodiment has awrite-read-write configuration, which may use shortened closures thatthus allow closer gap-to-gap separation.

Additional aspects of the embodiments shown in FIGS. 6 and 7 are similarto those given above.

A 32 channel version of a multi-module head 126 may use cables 350having leads on the same or smaller pitch as current 16 channelpiggyback LTO modules, or alternatively the connections on the modulemay be organ-keyboarded for a 50% reduction in cable span. Over-under,writing pair unshielded cables may be used for the writers, which mayhave integrated servo readers.

The outer wrap angles α₁ may be set in the drive, such as by guides ofany type known in the art, such as adjustable rollers, slides, etc. oralternatively by outriggers, which are integral to the head. Forexample, rollers having an offset axis may be used to set the wrapangles. The offset axis creates an orbital arc of rotation, allowingprecise alignment of the wrap angle α₁.

To assemble any of the embodiments described above, conventional u-beamassembly can be used. Accordingly, the mass of the resultant head may bemaintained or even reduced relative to heads of previous generations. Inother approaches, the modules may be constructed as a unitary body.Those skilled in the art, armed with the present teachings, willappreciate that other known methods of manufacturing such heads may beadapted for use in constructing such heads. Moreover, unless otherwisespecified, processes and materials of types known in the art may beadapted for use in various embodiments in conformance with the teachingsherein, as would become apparent to one skilled in the art upon readingthe present disclosure.

Conventional TMR structures have been developed strictly for non-contactrecording, such as hard disk drive (HDD) recording. Because the head innon-contact recording flies above the medium, there is no need formeasures for protecting the head from effects of head-media contact.However, conventional TMR structures, which implement a currentperpendicular to the plane (CPP) configuration, may exhibit propensityto develop electrical shorting when implemented in contact recordingenvironments, such as tape recording environments. Namely, contactbetween the magnetic medium and the sensor structure during contactrecording may deform the sensor layers and/or lead structures,effectively smearing the material of each of these layers across themedia facing side of the sensor structure, and thereby resulting inelectrical shorting of the TMR device. Once the device has beenelectrically shorted, it may be rendered non-functional.

Moreover, during the lapping that is performed to define themedia-facing surface and establish the sensor stripe height, materialsmay smear, resulting in electrical shorts that may significantly affectyield and even alter the performance of the finished head.

Materials, such as refractory metals, used in the non-magnetic portionof the TMR sensor shield-to-shield gap, are less susceptible todeformation and subsequent shorting is decreased compared to materialssuch as nickel chrome alloys. Other measures to alleviate shorting insuch conventional devices rely on increasing magnetic separation betweensensor and tape. In contact recording, there may be further increases inhead-tape spacing due to accumulations on the head. If large enough,these can lead to diminished signal output, reduced signal-to-noiseratio and/or resulted in otherwise non-optimal performance, ultimatelyleading to higher error rates, higher write skips and/or more frequentre-writes, loss of throughput and loss of capacity, all of which arehighly undesirable.

Wear particles, such as AlO₃, dispersed throughout a magnetic matrixcreate a highly wear-resistant tape. Similar to small sapphireparticles, wear particles reduce friction, thereby promoting durabilityof the tape. Moreover, wear particles may be intended to clean the headvia mild abrasion.

However, asperities on the tape surface may be present, e.g., such as aclump formed by an agglomeration of wear particles and binder or otherparticles. When these particle asperities on the tape pass over thesensor, deformation of the conductive metallic films near the tunneljunction may occur due to the contact with the asperity. Consequently,contact of the asperity on the films of the sensor exerts forces thatpush the metals sensitive to ductile bending in the direction of thetape movement, thereby causing the films to bend over on either side ofthe tunnel barrier layer. Iridium or other refractory metal spacerlayers are less susceptible to deformation than conventional metals usedin TMR heads, such as nickel chrome and permalloy. However, theserefractory metals may not be perfect in this respect.

In addition, asperities on the tape passing over the sensor may smearmaterial from the conductive metallic films across the tunnel junction,which in turn may cause shorting. Moreover, conductive metallic filmsnear the TMR that are susceptible to smearing may also have bendingductility that would lead to deformation of the head. Furthermore,deformed magnetic films may have a propensity to magnetically shield thesensor from the tape signal. A harder, less-ductile yet conductive metalor non-metallic material would be a desirable choice for the spacer nearthe TMR.

For current-in-plane (CIP) devices such as AMR and GMR sensors,pre-recession processing selectively etches the magnetic shields, thusfacilitating formation of protective insulating ‘walls’ that inhibitshorting due to tape-head contact. However, in CPP TMR sensors, thereare no insulating films in the sensor stack itself, apart from thetunnel barrier, to allow this methodology to work. Thus, while effectivefor AMR and GMR sensors, these methods may not adequately protectagainst shorting for TMR sensors when implemented in contact recordingenvironments.

Looking to FIGS. 8A and 8B, an apparatus 800 is illustrated, inaccordance with one embodiment. As an option, the present apparatus 800may be implemented in conjunction with features from any otherembodiment listed herein, such as those described with reference to theother FIGS. Of course, however, such apparatus 800 and others presentedherein may be used in various applications and/or in permutations whichmay or may not be specifically described in the illustrative embodimentslisted herein. Further, the apparatus 800 presented herein may be usedin any desired environment. Thus FIGS. 8A-8B (and the other FIGS.)should be deemed to include any and all possible permutations.

The apparatus 800 includes a sensor 802 having a media facing side 803,an active tunnel magnetoresistive region (TMR) region 804. The sensor802 also includes magnetic shields 806, 808 flanking (sandwiching) theTMR region 804, and electrically conductive, non-magnetic spacers 810,812 between the TMR region 804 and the magnetic shields 806, 808. Inaddition, between the non-magnetic spacers 810, 812, the TMR region 804sits on an antiferromagnetic layer 814 and has a sensor cap 816. Thesensor cap 816 may be comprised of multiple layers of conventionalmaterial, for example Ru—Ta—Ru, but could be other materials. Except asotherwise described herein, the various components of the apparatus ofFIGS. 8A-8B may be of conventional materials and designs, as would beunderstood by one skilled in the art. Moreover, except as otherwisedescribed herein, conventional processes may be used to form the variouscomponents of the various embodiments described herein.

Furthermore as shown in FIG. 8B, the active TMR region 804 includes afree layer 818, a tunnel barrier layer 820 and a reference layer 822e.g., of conventional construction. According to various embodiments,the free layer 818, the tunnel barrier layer 820 and/or the referencelayer 822 may include construction parameters, e.g., materials,dimensions, properties, etc., according to any of the embodimentsdescribed herein, and/or conventional construction parameters, dependingon the desired embodiment. Illustrative materials for the tunnel barrierlayer 820 include amorphous and/or crystalline forms of, but are notlimited to, TiOx, MgO and Al₂O₃.

As shown, the apparatus 800 may further include a durable layer 826above an upper one of the magnetic shields 808. In other embodiments, adurable layer 824 may additionally and/or alternatively be positionedbelow a lower one of the magnetic shields 806. The durable layer(s) 824,826 are preferably harder than the shield nearest thereto. Exemplarymaterials for the durable layer(s) 824, 826 include FeN, laminations ofpermalloy and FeN, etc. In other approaches, the durable layer(s) 824,826 may include a ferromagnetic layer of any suitable material, such as45/55 NiFe. Thus, the durable layer(s) 824, 826 may provide a wearsupport structure, which desirably allows for an improved resistance towear experienced on a media facing side of the sensor 802.

As shown in FIG. 8A, the apparatus 800 may also include insulatinglayers 828 interposed between hard bias layers 830 and the active TMRregion 804 to prevent parasitic current flow parallel to current flowthrough the sensor.

With continued reference to FIGS. 8A-8B, at least one of the spacers810, 812 between the sensor and the magnetic shields preferably includesan electrically conductive ceramic layer, which preferably is composedentirely of ceramic material. The other spacer may also have anelectrically conductive ceramic layer of the same or differentcomposition, and/or can include a layer of a metal or metallic alloy,can include a layer of a refractory material. In further approaches, theother spacer layer may be metallic or a metallic alloy. It should benoted that the spacers 810, 812 shown in the figures arerepresentational, and do not depict the various potential layers thereinthat may cumulatively form the spacers 810, 812 according to variousembodiments. Thus, according to some embodiments, one or both of thespacers 810, 812 may include layers in addition to the electricallyconductive ceramic layer, including, but not limited to seed layers(e.g., Cr, Ta, etc.), nonmagnetic spacer layers, antiferromagneticlayers, etc. For example, a seed layer may be disposed between theceramic material and a surface underlying the ceramic material. However,in other embodiments, the electrically conductive layer may form thewhole of one or both spacers 810, 812. Furthermore, there may be asecond electrically conductive ceramic layer between the active TMR andat least one of the spacers that include the first ceramic layer.

Depending on the desired embodiment, the electrically conductive layermay be formed using a single ceramic material; however, in otherembodiments, the electrically conductive layer may have a layeredstructure. Thus, an electrically conductive layer may be formed from anumber of sublayers, each of which may include a different ceramicmaterial according to any of those listed herein.

Illustrative thicknesses for the spacers 810, 812 and/or layer ofceramic material therein may be at least 2 nm per film, which may helpensure adequate crystallinity. Preferably, the thicknesses of thespacers 810, 812 and/or layer of ceramic material therein are at least 8nm, and ideally at least 10 nm.

Ceramic materials according to some embodiments tend to have highhardness and strength in compression. Illustrative materials for theelectrically conductive ceramic layer include ceramic materials that arehard, non-ductile and non-metallic (non-elemental metal), such as metalalloys, e.g. alumina and/or transition metal alloys, e.g., titaniumnitride, zirconia, ruthenium oxide, iridium oxide, etc., and/or siliconnitride or silicon carbide, and/or alloys thereof. However in otherembodiments, the ceramic material may include, but is not limited to, anelectrically conductive oxide, a conductive nitride, and/or a conductivecarbide.

The hardness of the ceramic material in the layer provides an advantageof reducing susceptibility to conductive bridging and at the same timenot requiring excessive head-tape spacing, such as may be needed forcoatings and pre-recession.

In one embodiment, the ceramic layer between the TMR and the magneticshields includes ruthenium oxide (RuO₂). RuO₂ is a surprisingly hardconductive ceramic having a Vickers hardness of 19.2 to 28.6 GPa, whichis significantly higher than the Vickers hardness of, for example,iridium (1.76-2.10 GPa). Moreover, as a conductive ceramic, RuO₂ hashigher electrical resistivity of ˜35 uohm-cm compared to ˜13 uohm-cm forTantalum (Ta), for example.

In one approach, the ceramic layer of the spacer between the TMR and themagnetic shields is at least partially crystalline. Preferably, the RuO₂in the ceramic layer is at least partially crystalline. Crystalline RuO₂may be grown using known techniques, for example, by room temperature DCreactive magnetron sputtering, which does not require post-depositionannealing, and thus is compatible with tape head wafer fabricationprocesses.

Furthermore, there may be a second electrically conductive ceramic layerbetween the active TMR and at least one of the spacers that include thefirst ceramic layer.

Note that while much of the present description is presented in terms ofa data transducer, the teachings herein may be applied to createelectronic lapping guides (ELGs), such as TMR ELGs. In one embodiment,the ELG is unconventionally formed with shields, and with a TMRstructure that may be otherwise conventional, but modified as taughtherein. This provides enhanced immunity to shunting caused by scratchingduring lapping, which was previously not possible due to smearing of theshield material during lapping.

Although the embodiments of FIGS. 8A-8B illustrate a single sensor 802,according to various other embodiments, an apparatus may include anarray of the sensors sharing a common media-facing surface. Depending onthe desired embodiment, the array of sensors may include any of thedesigns, e.g., materials, layer combinations, etc., e.g., as describedabove.

Moreover, for embodiments including an array of the sensors sharing acommon media-facing surface, the sensors may include any of thosedescribed herein, e.g., data readers, data writers, servo readers, etc.However, according to an exemplary embodiment, which is in no wayintended to limit the invention, an array of sensors sharing a commonmedia-facing surface may include only readers. In other words, nowriters would be present on the common media-facing surface of the arrayof sensors. For example, there may be no writers on the module at all,e.g., see 254 of FIG. 3 and 252, 256 of FIG. 4.

In some embodiments, the apparatus may include a drive mechanism forpassing a magnetic medium over the sensor e.g. see 100 of FIG. 1A; and acontroller electrically coupled to the sensor, e.g. see 128 of FIG. 1A.

Looking to FIG. 9, an apparatus 900 is illustrated, in accordance withone embodiment. As an option, the present apparatus 900 may beimplemented in conjunction with features from any other embodimentlisted herein, such as those described with reference to the other FIGS.Of course, however, such apparatus 900 and others presented herein maybe used in various applications and/or in permutations which may or maynot be specifically described in the illustrative embodiments listedherein. Further, the apparatus 900 presented herein may be used in anydesired environment. Thus FIG. 9 (and the other FIGS.) should be deemedto include any and all possible permutations.

The apparatus 900 includes a sensor 902 having a media facing side, andan active tunnel magnetoresistive region (TMR) region 904. The sensor902 also includes magnetic shields 906, 908 flanking (sandwiching) theTMR region 904, and electrically conductive, non-magnetic spacers 910,912 between the TMR region 904 and the magnetic shields 906, 908. Exceptas otherwise described herein, the various components of the apparatusof FIG. 9 may be of conventional materials and designs, as would beunderstood by one skilled in the art. Moreover, except as otherwisedescribed herein, conventional fabrication techniques may be used invarious embodiments.

Furthermore, the active TMR region 904 includes a free layer 918, atunnel barrier layer 920 and a reference layer 922 above anantiferromagnetic layer 914. According to various embodiments, the freelayer 918, the tunnel barrier layer 920 and/or the reference layer 922may include construction parameters, e.g., materials, dimensions,properties, etc., according to any of the embodiments described herein,and/or conventional construction parameters, depending on the desiredembodiment. Illustrative materials for the tunnel barrier layer 920include amorphous and/or crystalline forms of, but are not limited to,TiOx, MgO and Al₂O₃.

With continued reference to FIG. 9, a preferred embodiment includes anelectrically conductive ceramic layer 924 between the active TMR region904 and at least one of the spacers 910 or 912. According to someembodiments, ceramic layers may be positioned between the active TMRregion 904 and both of the spacers 910, 912.

It should be noted that the spacers 910, 912 shown in the figures arerepresentational, and do not depict the various potential layers thereinthat may cumulatively form the spacers 910, 912 according to variousembodiments.

Depending on the desired embodiment, the electrically conductive ceramiclayer 924 may be formed using a single ceramic material in one or morelayers; however, in other embodiments, the electrically conductive layermay have a layered structure where one or more of the layers is of aceramic material. Thus, for example, an electrically conductive ceramiclayer 924 may be formed from a number of sublayers, each of which mayinclude a different ceramic material according to any of those listedherein.

Illustrative materials for the ceramic layer 924 include materials thatare hard, non-ductile and non-metallic, such as ruthenium oxide, aluminaand/or transition metal ceramics. Additional examples include titaniumnitride, zirconia, iridium oxide, etc., and/or combinations of any ofthe foregoing. However in other embodiments, the ceramic material mayinclude, but is not limited to, an electrically conductive oxide, aconductive nitride, and/or a conductive carbide.

With continued reference to FIG. 9, at least one of the non-magneticspacers 910, 912 may include an electrically conductive layer whichcontains a refractory material, for example iridium, but could be otherconventional refractory material. It should be noted that the spacers910, 912 shown in the figures are representational, and do not depictthe various potential layers therein that may cumulatively form thespacers 910, 912 according to various embodiments. Thus, according tosome embodiments, one or both of the spacers 910, 912 may include layersin addition to the electrically conductive layer, including, but notlimited to seed layers (e.g., Cr, Ta, etc.), nonmagnetic spacer layers,antiferromagnetic layers, etc. For example, a seed layer 930 or 932 maybe disposed between the refractory material and a surface underlying therefractory material. However, in other embodiments, the electricallyconductive layer may form the whole of one or both spacers 910, 912.

In one embodiment, the ceramic layer 924 between TMR 904 and spacers910, 912 includes ruthenium oxide (RuO₂). The hard, non-ductileproperties of RuO₂ may minimize or eliminate bending ductility of themetal spacer layers 910, 912 immediately proximate to the TMR region904. For example, in FIG. 9, the ceramic RuO₂ layer 924 may be placedbetween the free layer 918 and an iridium spacer layer 912. Furthermore,the ceramic RuO₂ layer 924 may be sandwiched between ruthenium filmssuch that the RuO₂ interlayer 924 protects the free layer 918 frominterdiffusing into a capping layer 928, e.g., of Ta.

Illustrative thicknesses for the ceramic interlayer 924 and/or layer ofceramic material therein may be at least 2 nm per film.

In one approach, the ceramic material of the interlayer 924 between theTMR 904 and the spacers is at least partially crystalline. Preferably,the RuO₂ in the ceramic layer is at least partially crystalline.Crystalline RuO₂ can be grown by DC reactive magnetron sputtering atroom temperature and does not require post-deposition annealing, andthus is compatible with tape head wafer fabrication processes.

In an alternative embodiment of the sensor containing an interlayer ofceramic material 924 in the sensor cap 916, either one or both of thenon-magnetic spacers 910, 912 may also be comprised of ceramic materialas described in FIGS. 8A and 8B. If the non-magnetic spacer 910 or 912is comprised of ceramic layer, the seed layer 930 or 932 is notnecessary.

Moreover, for embodiments including an array of the sensors sharing acommon media-facing surface, the sensors may include any of thosedescribed herein, e.g., data readers, data writers, servo readers, etc.However, according to an exemplary embodiment, which is in no wayintended to limit the invention, an array of sensors sharing a commonmedia-facing surface may include only readers. In other words, nowriters would be present on the common media-facing surface of the arrayof sensors. For example, there may be no writers on the module at all,e.g., see 254 of FIG. 3 and 252, 256 of FIG. 4.

In some embodiments, the apparatus includes a drive mechanism forpassing a magnetic medium over the sensor e.g. see 100 of FIG. 1A; and acontroller electrically coupled to the sensor, e.g. see 128 of FIG. 1A.

It will be clear that the various features of the foregoing systemsand/or methodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

It will be further appreciated that embodiments of the present inventionmay be provided in the form of a service deployed on behalf of acustomer.

The inventive concepts disclosed herein have been presented by way ofexample to illustrate the myriad features thereof in a plurality ofillustrative scenarios, embodiments, and/or implementations. It shouldbe appreciated that the concepts generally disclosed are to beconsidered as modular, and may be implemented in any combination,permutation, or synthesis thereof. In addition, any modification,alteration, or equivalent of the presently disclosed features,functions, and concepts that would be appreciated by a person havingordinary skill in the art upon reading the instant descriptions shouldalso be considered within the scope of this disclosure.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of an embodiment of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

What is claimed is:
 1. An apparatus, comprising: a sensor having anactive tunnel magnetoresistive region, magnetic shields flanking thetunnel magnetoresistive region, and spacers between the active tunnelmagnetoresistive region and the magnetic shields, wherein the activetunnel magnetoresistive region includes a free layer, a tunnel barrierlayer and a reference layer, wherein at least one of the spacersincludes an electrically conductive ceramic layer.
 2. An apparatus asrecited in claim 1, wherein a thickness of the ceramic layer is at least2 nanometers.
 3. An apparatus as recited in claim 1, wherein a thicknessof the ceramic layer is at least 10 nanometers.
 4. An apparatus asrecited in claim 1, wherein the ceramic layer includes ruthenium oxide.5. An apparatus as recited in claim 4, wherein the ceramic layer issandwiched between ruthenium films.
 6. An apparatus as recited in claim4, wherein the ruthenium oxide in the ceramic layer is at leastpartially crystalline.
 7. An apparatus as recited in claim 1, whereinthe ceramic layer is at least partially crystalline.
 8. An apparatus asrecited in claim 1, wherein the ceramic layer includes at least onematerial selected from a group consisting of: alumina, titanium nitride,zirconia, ruthenium oxide, iridium oxide, silicon nitride, and siliconcarbide.
 9. An apparatus as recited in claim 1, comprising an array ofthe sensors sharing a common media-facing surface.
 10. An apparatus asrecited in claim 9, wherein no write transducers are present on thecommon media-facing surface.
 11. An apparatus as recited in claim 1,wherein the sensor is an electronic lapping guide.
 12. An apparatus asrecited in claim 1, wherein both spacers include an electricallyconductive ceramic layer.
 13. An apparatus as recited in claim 12,wherein the electrically conductive ceramic layer of one of the spacershas a different composition than the electrically conductive ceramiclayer of the other of the spacers.
 14. An apparatus as recited in claim1, wherein at least one of the spacers includes a metal.
 15. Anapparatus as recited in claim 1, wherein one of the spacers includes theelectrically conductive ceramic layer and another of the spacers ismetallic or a metallic alloy.
 16. An apparatus as recited in claim 1,comprising a durable layer above an upper one of the shields and/orbelow a lower one of the shields, the durable layer being harder thanthe shield nearest thereto.
 17. An apparatus as recited in claim 1,comprising a second electrically conductive ceramic layer between theactive tunnel magnetoresistive region and at least one of the spacers.18. An apparatus as recited in claim 1, comprising: a drive mechanismfor passing a magnetic medium over the sensor; and a controllerelectrically coupled to the sensor.
 19. An apparatus, comprising: asensor having an active tunnel magnetoresistive region, magnetic shieldsflanking the tunnel magnetoresistive region, spacers between the tunnelmagnetoresistive region and the magnetic shields, and an electricallyconductive ceramic layer between the active tunnel magnetoresistiveregion and at least one of the spacers, wherein the active tunnelmagnetoresistive region includes a free layer, a tunnel barrier layerand a reference layer.
 20. An apparatus as recited in claim 19, whereina thickness of ceramic layer is at least 2 nanometers.
 21. An apparatusas recited in claim 19, wherein the ceramic layer includes rutheniumoxide.
 22. An apparatus as recited in claim 21, wherein the ceramiclayer is sandwiched between ruthenium films.
 23. An apparatus as recitedin claim 21, wherein the ruthenium oxide in the ceramic layer is atleast partially crystalline.
 24. An apparatus as recited in claim 19,wherein the ceramic layer is at least partially crystalline.
 25. Anapparatus as recited in claim 19, wherein ceramic layers are positionedbetween the active tunnel magnetoresistive region and both of thespacers.